Last updated: May 2026
Twin Hearts ("we", "our", or "us") is a twin pregnancy companion app for expectant parents. This Privacy Policy explains what information we collect, how we use it, your rights under applicable data protection law (including the EU General Data Protection Regulation — GDPR), and how to contact us.
Twin Hearts is operated by Dylan Ndengu, based in the Netherlands. We are the data controller for the personal data described in this policy.
1. Information We Collect
We collect information you provide directly when using the app:
- Account information: your name and email address, used to create and identify your account.
- Pregnancy information: due date, gestational week, twin type (DCDA/MCDA/MCMA), and pregnancy-related preferences.
- Personal details (mama only, optional): date of birth, used to calculate age at due date; whether this is a first pregnancy. These fields are voluntary.
- Country (inferred): we infer your country from your device's locale setting (e.g. "GB" from "en-GB"). No GPS or IP-based location data is collected.
- Health data: maternal weight logs, blood pressure readings, symptom entries, baby kick counts, and scan measurements you choose to enter.
- Journal entries: notes, memories, and milestones you write within the app.
- Appointment records: upcoming appointments and visit notes you add.
- AI chat messages: messages you send to the Twin Hearts AI assistant, which may include health-related context you choose to share.
- Sonogram images: ultrasound photos you upload, stored locally on your device only.
- Push notification token: a device identifier used to deliver reminders and notifications you enable.
We do not collect any information without your direct input. We do not use advertising trackers, analytics SDKs, or third-party tracking of any kind.
2. Legal Basis for Processing
Under GDPR, we process your personal data on the following legal bases:
- Contract (Article 6(1)(b)): processing your account information, pregnancy data, and app content is necessary to provide the Twin Hearts service you signed up for.
- Explicit consent (Article 9(2)(a)): health and pregnancy data is special category data under GDPR. By ticking the consent checkbox during registration, you explicitly consent to us processing this data to operate the app. You may withdraw consent at any time by deleting your account.
- Legitimate interests (Article 6(1)(f)): security logging and rate limiting to protect the service and its users.
3. How We Use Your Information
We use the information you provide solely to:
- Operate and personalise the Twin Hearts app experience for you and your partner.
- Sync your pregnancy data between devices linked to the same pregnancy.
- Send you reminders and push notifications you have opted into (supplements, appointments, weekly milestones).
- Power AI-assisted features (the Twin Hearts AI chat and weekly briefings) by sending your messages and relevant pregnancy context to Anthropic's API via our own server. Your messages and pregnancy context (including any health information you share in chat) are transmitted to Anthropic to generate responses. We do not send your name, email address, or raw stored records (weight logs, blood pressure, etc.) to Anthropic unless you include them in a chat message yourself.
We do not sell, rent, or share your personal information with third parties for marketing purposes.
4. Data Storage and Security
Your data is stored securely using Google Firebase (Firestore), a cloud database hosted on Google's infrastructure. Access to your pregnancy data is restricted by security rules so that only you and your linked partner can read or write it.
Sonogram images are stored locally on your device and are never uploaded to our servers.
All data in transit is encrypted using TLS. Firebase ID tokens are verified server-side on every AI request; your Anthropic API key is never exposed to the client.
5. Third-Party Sub-Processors
Twin Hearts uses the following third-party services to operate. Each acts as a data processor under a Data Processing Agreement with their respective customers:
- Google Firebase / Firestore — data storage and authentication (firebase.google.com/support/privacy)
- Google Sign-In — optional sign-in method (policies.google.com/privacy)
- Expo / EAS — app build and push notification delivery (expo.dev/privacy)
- Anthropic — AI chat feature; processes messages and pregnancy context you send via chat. Anthropic does not use API data to train its models by default. (anthropic.com/privacy)
- Namecheap — web hosting for twin-hearts.com (namecheap.com/legal/privacy-policy)
6. Data Retention and Deletion
Your data is retained for as long as your account is active.
You may delete your account at any time from within the app (Settings → Delete account). When you delete your account, your data enters a 30-day recovery window during which you can restore it. After 30 days, all your personal data is permanently and irreversibly deleted from our systems, including your Firestore records and Firebase Auth account.
You may also request deletion by contacting us at hello@twin-hearts.com. We will action deletion requests within 30 days.
7. Children's Privacy
Twin Hearts is intended for use by adults (expectant parents aged 18 and over). We do not knowingly collect information from children under 16. If you believe a child has provided us with personal information, please contact us so we can delete it.
8. Your Rights Under GDPR
If you are located in the European Economic Area (EEA) or the United Kingdom, you have the following rights regarding your personal data:
- Right of access (Article 15): request a copy of the personal data we hold about you.
- Right to rectification (Article 16): request correction of inaccurate or incomplete data.
- Right to erasure (Article 17): request deletion of your data. You can do this directly in the app or by contacting us.
- Right to restriction (Article 18): request that we restrict processing of your data in certain circumstances.
- Right to data portability (Article 20): request a copy of your data in a structured, machine-readable format to transfer to another service.
- Right to object (Article 21): object to processing based on legitimate interests.
- Right to withdraw consent: where processing is based on your consent (including special category health data), you may withdraw it at any time by deleting your account. Withdrawal does not affect the lawfulness of processing before withdrawal.
- Right to lodge a complaint: you have the right to lodge a complaint with a supervisory authority. In the Netherlands, this is the Autoriteit Persoonsgegevens (autoriteitpersoonsgegevens.nl).
To exercise any of these rights, contact us at hello@twin-hearts.com.
9. Changes to This Policy
We may update this Privacy Policy from time to time. When we do, we will update the "Last updated" date at the top of this page. For material changes, we will notify you within the app. Continued use of the app after changes constitutes acceptance of the updated policy.
10. Contact Us
If you have any questions about this Privacy Policy or how we handle your data, please contact us:
- Email: hello@twin-hearts.com
- Website: twin-hearts.com